The advantages of transmitting signals optically, as opposed to transmitting them electrically, are well documented. Optical signal transmission reduces inductance, capacitance, resistance, and electro-magnetic interference, or EMI, encountered in electrical signal transmission. The reduction of inductance, capacitance resistance and EMI means that signals transmitted optically do not degrade as readily, and thus, that the signals can be transmitted at higher frequencies.
Prototype opto-electronic integrated circuits (OEICs), which are used to process optical signals, are now being built. These OEICs and their interconnections do not subject signals to the relatively high inductance, capacitance and resistance associated with electrical integrated circuits (ICs) and, in particular, associated with the transmission of signals to and from the ICs over wire leads. The OEICs, which receive and transmit signals over optical fibers, can thus receive and process signals at the higher frequencies.
The production and deployment of OEICs has not progressed nearly as much as has the production and deployment of ICs. One of the reasons for this is that the proper alignment of fibers or optical waveguides to OEIC emitters and receivers, which is critical to the successful transmission of optical signals, requires a degree of precision beyond that currently available for the assembly of IC chips into packages. Known OEIC systems currently actively align each optical fiber with an individual associated emitter or receiver, since they are not configured, nor are they configurable to align simultaneously large arrays of optical fibers or optical waveguides to large arrays of emitters and receivers on an OEIC. The known systems thus attach a fiber to a die on which the circuit is fabricated by (i) placing the fiber proximate to an emitter or receiver, (ii) moving or angling the fiber to a position which maximizes the light transmission over the fiber, and (iii) attaching the fiber to the die with an adhesive. While this technique produces chips with properly aligned input and output fibers, it is time consuming and thus expensive, and it does not lend itself to manufacture in quantity.